contentAreaFilled
Sets whether a button fills the area behind its content. Applies to everything built on a button.
A button stops taking this from the look and feel once the property is set, and Swing offers no way to hand it back.
This, rather than opaque(false), is how a button is made transparent: a look and feel paints the fill from this property, and keeps the opaque flag in step with it - for every button but a menu item, whose flag stands on its own.
Return
this modifier with content-area painting declared on it.
Parameters
filled
false leaves the area behind the text and icon unpainted, so whatever is behind the button shows through it.